Has anyone upgraded a domestic flight using a paper upgrade certificate, and then tried to use either the kiosk or web check in? Will the self-service check in work, or give you an error? I will be using paper upgrades and may be very short on time. I know that for instance the system might be able to print "collect upgrade" on the boarding pass, so it would not be entirely non feasible for the self-service check in systems to process paper upgraded reservations. Curious if anyone has tried this?

Nope, can't be done. In fact, you can't check in at the kiosk if you are upgrading a companion bc of your CP status. I've also had trouble checking in curbside bc of this. Just go to an agent and save yourself the aggravation.

MHT's got it. The only thing that I'd add would be to use web checkin to secure your checkin times, get your BP's for coach, and then goto the ticket counter to use the paper upgrades.

Good Luck!

-JC